Many different mouthwashes are available, some are better than others while others are no longer recommended.

Chlorhexidine digluconate 'Corsdyl'

This is a popular mouthwash with dentists and is often prescribed to patients with gum disease. This helps to kill bacteria in the mouth that cause 'gum disease'. One drawback is that the patient must brush their teeth before use as brown staining may occur on the teeth.
Dental floss allows the patient to access those areas which are missed by the toothbrush. The technique is quite simple and is more easily performed in front of the mirror.
The interproximal areas are difficult to clean with a toothbrush alone as the triangular area marked in red is not reached by the bristles. Plaque indicated in yellow can build up in these areas and dental floss is required to clean between the teeth efficiently.
The Technique

Take a piece of dental floss about 10 inches long. Wrap it around the fingers at each end then place it down between the teeth. Gently move it sideways, taking care not to injure the gum. The floss is removed by letting go of one end and pulling it though gently.
Certain areas are more susceptible to plaque and calculus formation, the diagram below illustrates this. By paying particular attention to these areas should decrease the build up of calculus and reduce the risk of tooth loss through gum disease.
Many people have crowded lower front teeth. Later in life many people loose these teeth to gum disease as cleaning is more difficult and the bone infront of some of the teeth is very thin and more easily destroyed.